Problem: 6 folders cost $5.70. Which equation would help determine the cost of 5 folders?
There are several equations that could help determine the cost, each with a slightly different approach. We can write the fact that 6 folders cost $5.70 as a proportion: $\dfrac{6}{\$5.70}$ Let $x$ represent the unknown cost of 5 folders. Since 5 folders cost $x$ , we have the following proportion: $\dfrac{5}{x}$ The cost changes along with the number of folders purchased, and so the two proportions are equivalent. $\dfrac{6}{\$5.70} = \dfrac{5}{x}$